Hugo Mercier is a researcher in cognitive science at the Institut Jean Nicod (Centre National de la Recherche Scientifique, École Normale Supérieure) in Paris, specializing in the study of reasoning and human communication. He is the author of a recently-published work on the way in which we resist attempts to influence us: Not Born Yesterday: the Science of Who We Trust and What We Believe.
Dan Sperber is a researcher in philosophy and cognitive and social science at the Institut Jean Nicod (Centre National de la Recherche Scientifique, École Normale Supérieure) in Paris. He is also professor at the Central European University in Vienna, and has taught at Princeton, and the Universities of Michigan, Chicago, and London. Among his books: Le Symbolisme en Général [Symbolism in General]; La Pertinence [Relevance]; Communication et Cognition [Communication and Cognition] (co-authored with Deirdre Wilson); and La Contagion des Idées [Contagious Ideas].

Reason, it has been said, is what makes humans so superior to the other animals. But if it is such an advantage, why has reason evolved only in our species? If reason is so reliable, why are our opinions and actions so often irrational? Hugo Mercier and Dan Sperber tackle this double enigma. Using historical examples, anecdotes from everyday life, and the most recent results of experimental psychology, they argue against the idea shared by philosophers and psychologists according to which reason’s primary function is to enable each person to achieve by him or herself a better understanding of the world and make the best decisions. Reason, they show, is above all a social tool: it helps us justify ourselves to others, to argue in order to convince others, and to evaluate the arguments others use to convince us. It facilitates communication, collective actions, and social life. It can also, however, polarize conflicts. Used in isolation, however, far from allowing us to make progress, it most often causes a person to spin his or her wheels.

In other words, the primary function of reason is to help humans make the most of their so very rich and complex interactions. This “interactionist” concept explains how reason has been able to evolve, what its place in our psyche truly is, what we can expect from it, and what would be pointless to ask of it.

Ambitious, provocative, fascinating, this book gives readers resources to rethink their own way of thinking.